Ashford Price, of the Dan-yr-Ogof caves, said he is determined to "get the title for Wales."

The caves are in pristine condition

Ashford Price, Dan-yr-Ogof caves

"We have done tremendously well to be in the top nine, the Jurassic Coast and the White Cliffs of Dover are hugely well known.

"But the support we are getting from Wales is great.

"We are getting calls from asking how they can vote and we have had tremendous support from the Brecon Beacons National Park and Powys Council," he said.

Mr Price, whose ancestors found the caves, said he had no idea it would be picked.

"We only heard about it when we received a letter. The caves are the finest preserved caves in Britain.

"They are in pristine condition. Ours was the first farm to diversify into tourism," he added.

Dan-yr-Ogof caves were discovered in 1912

Cwm Idwal, believed to be Wales' best example of a glacial valley, lies in the heart of the Snowdonia National Park.

Councillor Ieuan Llewelyn Jones said: "It has been regarded for a long time as a fine wonder, I'm not surprised at all it is on the list."

"It's a relic of the Ice Age and something really remarkable."

A Snowdonia National Park Authority spokesperson said: "Cwm Idwal is a very special place in terms of landscape, nature conservation and geology, indeed it was the first natural nature reserve in Wales.

"The cwm is visited by thousands of visitors every year and a favourite spot for many.

Four programmes on the natural wonders will be broadcast this summer.

Executive producer Bill Locke, said: "We've travelled the length and breadth of Britain from the Giant's Causeway to Cheddar Gorge and as far as windswept St Kilda battered by the Atlantic, to film our top 10 finest natural wonders."